Gravitational potential Definition and 389 Threads

Hi. I am a little confused about this: If I throw a stone straight upwards from the surface of the Earth, with the escape speed of 11,2 km/s, assuming that no air or other particles gets in the way, and waited for a very, very long time, the velocity of my stone (and the Earth in the...

Hi. Imagine a closed physical system (a universe) with only one star like our Sun, and one planet like our Earth, but so far away from each other, that the gravity from both matters only has a very small effect on each other. There is a (almost maximum) gravitational potential energy...

Gravitational potential energy usually arises due to the force of attraction experienced by a body. When a small body is placed between to massive bodies (not of equal masses) it is attracted by both. So when we consider the small body’s gravitational potential energy should we take the sum of...

Homework Statement when doing work on something how does work relate to the gravitational potential energy that it acquires? Homework Equations The Attempt at a Solution

Homework Statement A meter stick with a mass of .160kg is pivoted about one end so it can rotate without friction about a horizontal axis. The meter stick is held in a horizontal position and released. As it swings through the vertical, calculate (a) the change in gravitational potential...

The problem states that: "Bruce stands on a bank beside a pond, grasps the end of a 10.0m long rope attached to a nearby tree and swings out to drop into the water. If the rope starts at an angle of 35 degrees with the vertical, what is Bruce's speed at the bottom of the swing? Variables...

Consider a system containing multiple massive objects, where the field is weak everywhere and velocities are non-relativistic. In a linearized GR approximation (as for example described in Wald "General Relativity" section 4.4) described relative to a flat background coordinate system, we find...

E=mgh how to find the gravitational potential energy if the mass is not given only height is given E.G A man decides to cimb an office tower. If the floors are 3.8 m apart, how much gravitational potential energy would the man have relative to the ground floor if he made it to 5th floor??

Homework Statement i have to determine the potential energy of a satellite around a circular orbit and i have been given the radius of the circular orbit is 3Re and mass of a satellite of 5.00*10^2 -- ONLY Homework Equations so can use the Gmm/r... and subsitute the mass of the...

Homework Statement A 78.9-kg skier rides a 3150-m-long lift to the top of a mountain. The lift makes an angle of 11.9 ° with the horizontal. What is the change in the skier's gravitational potential energy? Homework Equations W=mgcos\theta(ho-hf) The Attempt at a Solution...

[SOLVED] Gravitational potential energy edit: solved

The gravitational potential energy W of a self-gravitating sphere of mass M and radius R depends on the detailed distribution of mass within the sphere, but it is generally of order of magnitude -GM^2/R. For the Sun, W_sun = -2G(M_sun)^2/R. What is the timescale t = -(1/2)(W_sun)/(L_sun) over...

ok I am in high school and have a physics challenge, its a device that transports a mass of 305 grams (Tomato soup can), a distance of 4 meters. no chemical, elastic, spring, electrical or magnetic energy can be used - the only energy source for propelling the device will come from the...

ok I am in high school and have a physics challenge, its a device that transports a mass of 305 grams (Tomato soup can), a distance of 4 meters. no chemical, elastic, spring, electrical or magnetic energy can be used - the only energy source for propelling the device will come from the...

Homework Statement A 7.26 kg ball hangs from end of 2.5 m rope. The ball is pulled back until rope makes 45 degree angle with vertical. What is the gravitation potential energy? Homework Equations ug=mgh The Attempt at a Solution I thought I would just multiply mass times gravity...

if we think the height of a matter reaches over the radius of the Earth how will the potential energy of it change? when height of it approaches infinite from zero how will be the graph of gravitational potential energy-height? thank you

Homework Statement Consider a thin ring of radius a and mass M. A mass m is placed in the plane of the ring (not in the center!). Determine the gravitational potential for r < a. Find a position of equilibrium and determine whether it is stable or unstable. (Hint: Consider a small...

[SOLVED] Gravitational Potential Energy Problem Homework Statement Suppose that the moon were at rest at its present distance from the earth, rather than orbiting it. With what speed would it strike the earth? (Take the Earth to be infinitely massive relative to the moon) Homework...

A 65 kg diver is standing on a diving platform 10.0 m above the water. What is the gravitational potential energy of the diver with respect to the water’s surface? I know this one,,, Ep = mgh e= 65*10* 9.8 = 6370 Joules or 6.37 kilojoules If the diver in question 6 falls from the...

Gravitational potential energy. Please help! Homework Statement A projectile is launched from Earth's surface at a speed of 10 km/s. Find the maximum height it reaches. Homework Equations change in U = -change in K U = -GM/r The Attempt at a Solution GMm/r = 1/2mv^2...

Hey guys, I am involved in a competition where my objective is to build a Joule Car: Can anyone please give me ideas of how I can use gravitational potential energy to build it? Here are the actual directions: http://www.mrmaloney.com/nssl/events/2007-2008/0708_3-dec-joule-car.pdf Your help...

The answer is c, but I can't figure out what is the reason, can somebody kindly explain it? http://tinyurl.com/32322t

[SOLVED] Gravitational Potential Energy Homework Statement Calculate the change in potential energy of a 77.2-kg man when he takes an elevator from the first floor to 24th floor, if the distance between floors is 4.05 m. Homework Equations Ug = mgy The Attempt at a Solution Ug =...

hi, please help me figure these problems out. much appreciated. 1. an object of mass .7kg is thrown vertically upwards at a speed of 29 m/s. What is the gravitational potential energy of the obect at the highest point of its trajectory? 2. an object of mass 8.9kg moves with initial speed...

Homework Statement A baseball is thrown from the roof of a 22.0-m-tall building with an inital velocty of magnitude 12.0 m/s and directed at an angle of 53.1 degrees above the horizontal. a) What is the speed o fthe ball just before it strikes the ground? Use energy conservation and ignore...

Homework Statement Ok, I am deriving the change in gravitational potential energy at the surface of the Earth and have met with some difficulties. Homework Equations g=GM/r^2 P.E.=-GMm/r The Attempt at a Solution \delta P.E. = -GMm/r_f+GMm/r_i Where r_f > r_i Since...

Homework Statement A mail bag with a mass 120kg is suspended by a vertical rope 8.0m long. a.) What horizontal force is necessary to hold the bag in a position displaced sideways 4.0m from its initial position? b.) How much work is done by the worker in moving the bag to this position...

Hello. I'm new. I was looking around on the web a bit to find an answer to my problem, and I came across these forums. Gravitational force = -GMm/(r^2) Gravitational force between a small mass (m) and the Earth (M) is zero at a distance of infinity. Any distance smaller than infinity gives...

I'm going through The Feynman Lectures On Physics. I've taken a few classical physics classes before, however Feynman's detailed explanations are much better than anything I've gotten from my teachers. However, I'm having a little difficulty following the mathematics when he tries to show that a...

Homework Statement Two Jupiter-size planets are released from rest 1.30×10^11 m apart. What are their speeds as they crash together? Homework Equations The Attempt at a Solution I have done K_f + U_f = K_i + U_i with K_i being zero because they have crashed together so... K_f + U_f = U_i...

Homework Statement A binary star system has two stars, each with the same mass as our sun, separated by 1.00×10^12 m. A comet is very far away and essentially at rest. Slowly but surely, gravity pulls the comet toward the stars. Suppose the comet travels along a straight line that passes...

Homework Statement a rocket of mass 1.5e6 kg is launched upward from the surface of the Earth (mass Me =5.97e24, radius Re = 6.38 X 10^6m) with a speed of 0.5 x 10^4 m/s. What is the maximum altitude the rocket will reach above the surface of the Earth? Homework Equations 1/2 mv1^2 -...

1. A spring is suspended froma ceiling and a 256 g mass is attached to it and pulled down to stretch the spring by 18.2 cm. THe mass is released and travels through the equilibrium position with a speed of 0.746 m/s. Calculate the force constant of the spring/ 2. 1/2kx^2 = Ee 1/2mv^2 =...

Homework Statement http://img256.imageshack.us/img256/795/untitledpw7.jpg The Attempt at a Solution I know Ug stands for the gravitational potential energy, but I'm not sure what Us and Uint stands for. At initial stage 1, I know the ball has kinetic energy and also has had work...

This paper conjectures a relation between the gravitational potential and the value of the Fine Structure Constant. Although a key constant in all electromagnetic quantum and quantum field theories, accept for some numerology manipulations, the value of the Fine Structure Constant is not...

There is a graph saying that at r=1.0 is the center of the moon.. A satellite of mass 1500 kg is launched from the surface of the planet. Determine the minimum kinetic energy at launch the satellite must have so that it can reach the surface of the moon. The surface of the moon is r=...

Homework Statement determine the amount of work required to move a satellite from orbital radius of 2r_e (twice the radius of the earth) to 3r_e, if it has a mass of 500 kg? Homework Equations Find change in Gravitation potential energy and also the change in the kinetic energy The...

I have an idea I would like to analyze but I'm practically ignorant of physics and engineering so I'm hoping you folks can give me some informative feedback. First, something tells me this idea is ridiculously uneconomical and/or impractical, but I'm still curious to find out and it will be a...

In a previous thread, I described a "double potential energy paradox". I allowed the discussions to stray off topic (resulting in locking of the thread), and I also thought someone had found a promising way to resolve the paradox. However, the main point was actually left unresolved, and I'm...

I'm confused about the two equations: PE_{G}=G\frac{m1*m2}{r} PE_{G}=mgh When do you use either of these equations? Can these two equations be used interchangeably or not? Also, I think I remember reading somewhere that you need to use the 1st equation when the problem involves large...

mistake in proof of gravitational potential equation? Hi, I have a problem in deriving an equation for the gravitational potential. Well, I think that the graviational potential is the work done by external forces in moving a unit mass Mp from infinity to that point through distance d, and...

why gravitational potential energy is negative?

Homework Statement By considering the gravitational potential energy of an object at the surface , find an expression for the escape speed from the surface and determine its value. Homework Equations GPE= mgh The Attempt at a Solution KE= 1/2* m * v^2 GPE= mgh GPE+ KE = 0...

Pe = Potential energy Ke = kinetic energy i want to clear up some confusion in me... firstly...it is true to say that potential energy transforms into kinetic energy as an object...correct? then the definition of an ORBIT is constantly falling around a planet, non-stop... therefore...

Hi guys...something does not seem right in physics... escape velocity is defined as the initial velocity required by a projectile to rise vertically and just escape the gravitational field of a planet and gravitational potential energy = 0 only at infinity displacement from planet (i.e...

hi, I came across a question in my physics textbook that I didn't get, so I was hoping that you guys could help me out a bit. :smile: Here's the question. It's about gravitational potential energy, by the way. ** On your desk you have N identical coins, each with a mass m. You stack the...

Homework Statement My question is, if your at the top of an apartment building, maybe the 10th floor, and you have a cup of water in your hand or on the table. Does the water have a higher gravitational potential energy than a cup of water at ground level? Homework Equations The...

Gravitational Potential Energy Problem I have this problem and it has been bugging me The problem (if i recall correctly) went like this: Ive got an Earth like object ( m = 6E24 kg) that will fall 1 A.U = 1.5E11 m towards a neutron star with a radius of 1E4 m. At this point it will...

Homework Statement Tarzan, in one tree, sights Jane in another tree. He grabs the end of a vine with length 20 m that makes an angle of 45 degrees with the vertical, steps off his tree limb, and swings down and then up to Jane's open arms. When he arrives, his vine makes an angle of 30...

I've recently noticed a very simple paradox in semi-Newtonian gravity which seems to say that there must be some rest energy in the field. However, this obviously conflicts with the GR position. I'm wondering if anyone can spare a moment to clarify the resolution of this paradox. In...